Power amps for stacked QUAD 57

[muimui]

Hello everyone
I will soon have four QUAD 57s which will be stacked as a stereo pair. Two QUAD 405 amps / QUAD 24 preamp will be used. I also have a pair of VTL mono 100s. Could one use the VTLs to drive the stacks? What is the best way to hookup the 57s? Any suggestions for building the stands for stacking the 57s is appreciated.
Muimui

[Light Dependant Resistor]

Hi
Similarly I have stacked 57's here. a pair from 1961 and a pair from 1968

The impedance the Quads provide is to quote a recent misused word, a nightmare,
they dip to 2 ohms at high frequencies and 15 ohms at other frequencies.

With 405's you should have the limiter Quad can provide for the 57
as the 405's power output is really too high, but if used sensibly, OK.

ESL57's demand the very best source preamp and power amps and
they will leave you searching for even better than Quads amplification.
The 34 may look nice but it is way off the mark, with what is possible
to achieve with the 57. Quad wasted their time with it,

My opinion is Peter Walker purpose built the 303 amp for the ESL57
although standard 405's will work, they sadly are not as good with the 57.

Over many years I have collected amplifiers just for the Quads
including 4x 50E which I think are going to be outstanding, I just need
to refresh some components in them. I presently use mine with a pair of 306's

The Net Audio Mk3 405 boards are a big improvement and work well
with the 57's, so perhaps contemplate upgrading the internal circuit boards
when you can. With the Net Audio boards you receive either the opa604 or
opa627 op amp, a much better device than the TL071 Quad used
( earlier the LM301 that is not much better than a noise generator )

Regarding your mono block VTL's they should be OK with one pair but
not both, as impedance is way too low for parallel wiring.

Some stand images here: https://www.google.co.nz/search?q=Stacked+ESL57+Stands&client=opera&hs=u9j&biw=1022&bih=476&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwju1MOaqKPJAhXB5aYKHRtbAhwQsAQIGQ

With stands try to keep the original look as much as possible.
Sheldon Stoke's site is one of the best: http://www.quadesl.com

Cheers / Chris

[Ali Tait]

Some Class D amps would be suitable, such as the Hypex NCore modules.

[Light Dependant Resistor]

Some Class D amps would be suitable, such as the Hypex NCore modules.

Yes the NCore have some impressive figures, the end result being to use available power, which the Ncore has in abundance, sensibly.:)

The ESL57 is in many ways unique in terms of its load presented to amplifiers being capacitive / reactive and like a mountain with impedance.
Looking back at some of Quads designs - there was in the case of a 50E a transformer on the amplifier output then driving a transformer
in the speaker. Similarly in the 303 a capacitor driving a transformer, so always a coupling medium. The 405 departed from this recipe
and it is more forward in its presentation, the Net Audio Mk3 boards being much better in sound quality if a 405 is used. .

A look at amplifiers for the 57 is here: http://www.quadesl.org/index.php/hard-core/amplifiers/christian-steingruber

From my observations the ESL57 is in many ways the perfect speaker, but at the same time demanding in where it
can be located. The key to getting them to do what they are really capable of is lowering distortion from ancillary equipment
and particularly the source components and preamp.


Cheers / Chris

[Audio Advent]

I heard some stacked quads once and they were powered by something like a large Plinius mono blocks but with some One Thing Audio doobery to protect against those low impedances (or something). But they sounded great.